Corticotrophin-releasing factor (CRF) plays a major role in coordinating stress responses. We aimed to test whether blocking endogenous CRF activity can prevent the stress-induced dilation of intercellular spaces in esophageal mucosa. Eighteen adult male rats were divided into 3 groups: 1) a non-stressed group (the non-stressed group), 2) a saline-pretreated stressed group (the stressed group), 3) and an astressin-pretreated stressed group (the astressin group). Immediately after completing the experiments according to the protocol, distal esophageal segments were obtained. Intercellular space diameters of esophageal mucosa were measured by transmission electron microscopy. Blood was sampled for the measurement of plasma cortisol levels. Mucosal intercellular spaces were significantly greater in the stressed group than in the non-stressed group. Mucosal intercellular spaces of the astressin group were significantly smaller than those of the stressed group. Plasma cortisol levels in the stressed group were significantly higher than in the non-stressed group. Pretreatment with astressin tended to decrease plasma cortisol levels. Acute stress in rats enlarges esophageal intercellular spaces, and this stress-induced alteration appears to be mediated by CRF. Our results suggest that CRF may play a role in the pathophysiology of reflux-induced symptoms or mucosal damage.